The present invention relates to data storage systems, and more particularly, this invention relates to textured surfaces on a magnetic head.
In magnetic storage systems, data is read from and written onto magnetic recording media utilizing magnetic transducers commonly. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.
An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.
In a tape drive system, magnetic tape is moved over the surface of the tape head at high speed. This movement generally entrains a film of air between the head and tape. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial so that the recording gaps of the transducers, which are the source of the magnetic recording flux, are in near contact with the tape to effect efficient signal transfer, and so that the read element is in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read element.
Thin film magnetic heads are fabricated by building thin film devices on a ceramic substrate commonly referred to as a “wafer.” Common wafer materials include alumina-titanium carbide (Al2O3—TiC) composites, collectively referred to as AlTiC, and which are generally electrically conductive and typically comprise approximately 30-35% by weight TiC.
After polishing and other processing, the TiC grains 302 in a wafer substrate 306 of a new magnetic head typically protrude above the surrounding alumina 304 as illustrated in FIG. 3A. The TiC grains 302 may protrude above the surface 308 of the surrounding alumina 304 by a distance a of approximately 7 nm and the surface roughness (“Ra”) may be between approximately 2 nm to approximately 3 nm. The TiC grains 302 are considerably harder than the alumina 304 of the wafer substrate 306.
After a short period of tape contact during use, the TiC grains 302 tend to wear quickly to about the level 308 of the alumina due to mechanical shearing and oxidation as illustrated in FIG. 3B. Here, the Ra can drop to below 1 nm. At this point, undesirable head-to-tape interface (HTI) stiction forces are believed to be the highest.
Stiction forces at the HTI of a tape drive are a significant issue. The stiction forces can be so high that a drive cannot move the tape during operation. If excessive force is used to move the tape, the tape may be damaged or even break. In addition, if TiC grains protruding from the surrounding alumina break off of the surface of the wafer substrate during use, the separated TiC particles may be pushed through the sensor area by the tape, causing shorting and premature head wear. Therefore, a better way of avoiding the problems caused by stiction would be beneficial.